During the play of various sports, as well as in the context of various non-athletic activities, a person may rapidly alter motion so as to move in a sideways direction. In basketball and various other sports, for example, a player may frequently change direction of movement (or commence moving) by “cutting” quickly to one side. During such rapid sideways maneuvers, a person may push on the lateral side of one foot (i.e., the right foot when cutting left, the left foot when cutting right). That person may also (or alternatively) push against the medial side of the other foot (i.e., left foot when cutting left, right foot when cutting right).
To avoid performance degradation and/or injury in activities that involve rapid sideways maneuvers, a shoe designed for such activities should constrain a wearer's foot from unnecessary motion within the shoe. Conventionally, such constraint has been achieved by cinching laces and/or external straps to tighten the shoe upper. If the sole structure of the shoe is appropriately sized relative to the wearer's foot, the tightened upper can then prevent (or at least restrict) movement of the foot relative to the sole structure. Stabilizing a foot relative to a sole structure can provide significant performance and safety benefits.
In many cases, however, simply tightening an upper is insufficient to prevent a foot from moving across an underfoot platform. For example, a sole structure may have a footbed that is slightly wider than an optimum width for a particular wearer's foot. This is often the case for persons with narrow feet. If a sole structure underfoot platform is slightly wide for a particular wearer, there may be excess space between the sides of a wearer foot and the sides of the footbed. Under such circumstances, tightening laces or otherwise tightening the upper (even to a point that may cause discomfort) may not conform the upper to the wearer foot in regions adjacent to the footbed edges. In particular, such tightening will generally not pull the upper away from a “bite line” along which the upper is joined to an underfoot platform. If the upper does not fully conform to the wearer foot, gaps between the side of a wearer foot and the bite line can remain after the upper has been fully cinched. These gaps then provide room for the foot to move across the footbed during rapid sideways maneuvers.